java分页查询--oracle

在不改变报表查询所有数据的sql的基础上，调用一个方法来使sql变成分页查询：（在没有order by 的基础上）

public static void main(String[] args){
        StringBuffer sql = new StringBuffer();
        sql.append(" select uid,uname,usex,uage "); 
        sql.append(" from person where 1=1 ");
        
        String[] fields = { "id","name","sex","age"};    
      
        page( sql.toString(), fields);
      //  System.out.println( str.replaceFirst("select", "select rownum as rowno ,") );
    }

//分页通用
    public String page(String sql,String[] fields){
        String json="";
        //根据查询条件获得的总数量
        String totalsql="select count(1) " +sql.substring(sql.indexOf("from"));
        int totalSize=getTotalSize(totalsql);
        System.out.println("分页通用totalSize:"+totalSize);
        if(totalSize>0){
            //每页大小
            int pageSize = this.request.getParameter("pageSize");//第几页
            String startPage=this.request.getParameter("startPage");
            //用来看第几页的数据
            int currentPage = 0;
            if (startPage != null) {
                currentPage = Integer.parseInt(startPage);
            }
            //一共多少页
            int pageCount=totalSize%pageSize==0 ? totalSize/pageSize : totalSize/pageSize+1;
            //从第多少条数据开始，到多少条截止 
            int startCount=0;
            int endCount=0;
            if(currentPage !=0){
                startCount=currentPage*pageSize- pageSize + 1;
                if(currentPage*pageSize <= totalSize){
                    endCount=currentPage * pageSize;
                }
                if(currentPage*pageSize > totalSize){
                    endCount=totalSize % pageSize+(currentPage-1)*pageSize;
                }
            }
　　　　　　　//注意，将 select 替换后，sql 变成了  select rownum as rowno ,uid,uname,usex,uage from person where 1=1
            sql=sql.replaceFirst("select", "select rownum as rowno ,");  
            StringBuffer fysql=new StringBuffer(" select * from( "); 
           　//注意 fysql 是：  select * from( select rownum as rowno ,uid,uname,usex,uage from person where 1=1 and rownum<=10 ) table_alias  where table_alias.rowno>=1
　　　　　　　fysql.append(sql);
            fysql.append(" and rownum<= ")
                    .append(endCount)
                    .append(" ) table_alias")
                    .append(" where table_alias.rowno>=")
                    .append(startCount);
            System.out.println("分页通用sql:"+fysql);
            List list = getYSList(fysql.toString());
            JacksonUtil util=new JacksonUtil();
            json=util.writeArrayJSON(fields, list);
            json="{pager:{pageCount:"+pageCount+",recordCount:"+totalSize+"},data:"+json+"}";
            printResult("success", json);
        }else{
            json = "{pager:{pageCount:0,recordCount:0},data:[]}";
            printResult("success", json);
            
        }
        return null;
        
    }

根据查询条件获得的总数量

 public int  getTotalSize(String strSql) {
           
            Statement stmt = null;
            ResultSet rs = null;
            int totalSize=0;
            try
            {
　　　　　　　　//数据库的连接
              Class.forName("oracle.jdbc.OracleDriver");
              conn = DriverManager.getConnection("jdbc:oracle:thin:@127.0.0.1:1521:oa", "123", "123");
              stmt = conn.createStatement();
              rs = stmt.executeQuery(strSql);
             if(rs.next()) {
               totalSize=Integer.parseInt(rs.getString(1));
              }
              rs.close();
              stmt.close();
              conn.close();
            } catch (Exception e) {
              e.printStackTrace();
            } finally {
              if (rs != null) {
                  rs = null;
                }
                if (stmt != null) {
                  stmt = null;
                }
                if (conn != null){
                  conn = null;
               }return totalSize;
          }
}